As a DM reader, it may not matter so much.
But, as a player, it would be too easy to see or accidently notice/skim stuff that is currently in Dungeon if it were all in the same magazine. If I wre the DM for those players, I would not want to make it so easy for the players to notice (even if casually or on accident) the same material I am using for inspiration on what will be surprising them in the next session.
Sure, they can easily look now but it takes just a little more effort for someone doing it on purpose, but you won't have the accidental noticing of the content if it were all in one magazine mixed together in the same pages.